Heater Core Shut-Off Valve

A buddy has an A100 Pick-Up with a 360/727 in it. It gets very warm in the cab in the summer. Would a shut off valve in one of the heater hose lines help with the in cab heat?
He does NOT want to eliminate the heater core altoghther as he does/will drive when the colder weather arrives. He just wants the quick option to either have coolant flow through the heater core (valve open) or to stop the coolant flow (valve closed).
He was thinking of using a simple ball/cock plumbing valve from Home Depot/Lowes.
Any thoughts??
Author: admin